diff -rupN pjproject-2.5.5/pjsip/src/pjsip/sip_transport.c pjproject-2.5.5-new/pjsip/src/pjsip/sip_transport.c
--- pjproject-2.5.5/pjsip/src/pjsip/sip_transport.c	2016-02-25 05:38:34.000000000 +0100
+++ pjproject-2.5.5-new/pjsip/src/pjsip/sip_transport.c	2017-01-05 14:15:09.069519967 +0100
@@ -1248,22 +1248,22 @@ PJ_DEF(pj_status_t) pjsip_tpmgr_register
 
     pj_lock_acquire(mgr->lock);
 
-    /* Check that no factory with the same type has been registered. */
+    /* Check that no factory with the same type and bound address has been registered. */
     status = PJ_SUCCESS;
     for (p=mgr->factory_list.next; p!=&mgr->factory_list; p=p->next) {
-	if (p->type == tpf->type) {
-	    status = PJSIP_ETYPEEXISTS;
-	    break;
-	}
-	if (p == tpf) {
-	    status = PJ_EEXISTS;
-	    break;
-	}
+        if (p->type == tpf->type && !pj_sockaddr_cmp(&tpf->local_addr, &p->local_addr)) {
+            status = PJSIP_ETYPEEXISTS;
+            break;
+        }
+        if (p == tpf) {
+            status = PJ_EEXISTS;
+            break;
+        }
     }
 
     if (status != PJ_SUCCESS) {
-	pj_lock_release(mgr->lock);
-	return status;
+        pj_lock_release(mgr->lock);
+        return status;
     }
 
     pj_list_insert_before(&mgr->factory_list, tpf);
@@ -2047,13 +2047,11 @@ PJ_DEF(pj_status_t) pjsip_tpmgr_acquire_
 	pj_memcpy(&key.rem_addr, remote, addr_len);
 
 	transport = (pjsip_transport*)
-		    pj_hash_get(mgr->table, &key, key_len, NULL);
-
+    pj_hash_get(mgr->table, &key, key_len, NULL);
+    unsigned flag = pjsip_transport_get_flag_from_type(type);
 	if (transport == NULL) {
-	    unsigned flag = pjsip_transport_get_flag_from_type(type);
 	    const pj_sockaddr *remote_addr = (const pj_sockaddr*)remote;
 
-
 	    /* Ignore address for loop transports. */
 	    if (type == PJSIP_TRANSPORT_LOOP ||
 		     type == PJSIP_TRANSPORT_LOOP_DGRAM)
@@ -2135,6 +2133,11 @@ PJ_DEF(pj_status_t) pjsip_tpmgr_acquire_
 	    }
 
 	} else {
+        /* Make sure we don't use another factory than the one given if secure flag is set */
+        if (flag & PJSIP_TRANSPORT_SECURE) {
+            TRACE_((THIS_FILE, "Can't create new TLS transport with no provided suitable TLS listener."));
+            return PJSIP_ETPNOTSUITABLE;
+        }
 
 	    /* Find factory with type matches the destination type */
 	    factory = mgr->factory_list.next;